#  The line above is intentionally blank
#+
#  Name:
#     gif2ndf
 
#  Purpose:
#     Converts a GIF-format file into an NDF 
 
#  Type of Module:
#     Bourne shell script
  
#  Description:
#     This Bourne-shell script converts a Graphics Interchange Format
#     (GIF) file into an unsigned-byte (256 grey-level) NDF format file.
#     It handles one- or two-dimensional images.  The script uses
#     various PBMPLUS utilities to produce a FITS file, flipped top
#     to bottom, and then FITS2NDF to produce the final NDF.  Error
#     messages are converted into Starlink style (preceded by !).

#  Usage:
#     gif2ndf in [out]

#  Parameters:
#     IN = FILENAME (Read)
#        The name of the GIF file to be converted (without the .gif extension
#        which is assumed).
#     OUT = NDF (Write)
#        The name of the NDF to be generated (without the .sdf extension).
#        If the OUT parameter is omitted, the value of the IN parameter
#        is used.
 
#  Examples:
#     gif2ndf old new
#        This converts the GIF file old.gif into an NDF called new
#        (in file new.sdf).
#     gif2ndf horse
#        This converts the GIF file horse.gif into an NDF called horse
#        (in file horse.sdf).

#  Related Applications:
#     CONVERT: NDF2GIF

#  Notes:
#     This initial version of the script generates images with at most
#     256 grey levels.  It does not use the image colour lookup table.
#
#     Input image filenames must have the extension .gif.
#
#     The PBMPLUS utilities giftopnm, ppmtopgm and pgmtofits 
#     must be available on your PATH.
 
#  Authors:
#     MJC: Malcolm J. Currie (STARLINK)
#     GJP: G.J.Privett (Starlink - UWCC)
#     AJC: A.J.Chipperfield (Starlink - RAL)
#     {enter_new_authors_here}
 
#  History:
#     28-NOV-1995 (AJC):
#        Original version, based on work by MJC and GJP.
#     1997 August 1 (MJC):
#        Removed KAPPA dependencies.  Reworded and reordered the
#        description.  Added some comments.
#     1997 October 3 (MJC):
#        Improved the parameter handling to allow for no arguments, and
#        to remove any .gif that may be present in the first argument.
#     {note_further_changes_here}

#  Bugs:
#     {note_any_bugs_here}
 
#-

# Check that a file name was given.
if [ "$#" -eq 0 ]
then
   echo "!! GIF2NDF: no GIF name supplied"
   echo "!  Usage: gif2ndf in [out]"
   exit
fi

# Remove any .gif file extension.
root=`echo $1 | sed 's#.gif##'`

# Find the filename less any path.
name=`basename $root`

# Set required output file name.  Defaults to the input name.
out=${2:-$name}

# Convert the image removing temporary files at each stage.  The PMBPLUS
# utilities giftopnm, ppmtopgm and pgmtofits must be available on your
# path.
#
# Convert image from GIF format to FITS, flipping it from top to bottom.
# The error output is written to temporary files.  Make the error look
# as if it came from MSG.
giftoppm ${root}.gif 2> convert_err1_$name.lis | \
ppmtopgm 2> convert_err2_$name.lis | \
pnmflip -topbottom 2> convert_err3_$name.lis | \
pgmtofits 2> convert_err4_$name.lis > convert_temp_$name.fit || \
  { sed 's/^/!  GIF2NDF:/' convert_err?_$name.lis 1>&2
    rm -f convert_err?_$name.lis convert_temp_$name.fit
    exit 1
  }
  rm -f convert_err?_$name.lis
 
# Convert the image to an NDF of data type _UBYTE.  Make the error look
# as if it came from MSG, so as this is a secondary error report, 
# replace the !! prefix with !.
$CONVERT_DIR/fits2ndf in=convert_temp_$name.fit out=$out fmtcnv=t \
  </dev/null  2>&1 | \
  sed 's/^\!\!/\! /' | \
  awk \
'BEGIN{err=0}\
/^\!/{if(err==0){err=1;print "!! GIF2NDF: Error reports from FITS2NDF"}};\
{print}\
END{if(err==1){exit 1}}' || \
  (rm -f convert_temp_$name.fit
   echo "!  GIF2NDF: Abandoned at FITS2NDF"
   exit 1
  ) || exit 1
  rm -f convert_temp_$name.fit